A film-sheet releasing device of this type is known (DE-OS 30 00 760). The known device is associated with a slider provided in a cassette unloading and reloading apparatus for aligning and positioning an X-ray film cassette in the cassette unloading and reloading station of the apparatus. The slider is located laterally above a transport belt by means of which an X-ray film cassette is transported from an input point up to a final abutment in the unloading and reloading station. If an X-ray film cassette is present in the unloading and reloading station, it is brought into contact with a stationary abutment ledge opposite to the slider when said slider moves laterally towards the X-ray film cassette. The film-sheet releasing device consists of a number of probes in the form of blast tubes (air nozzles) which are arranged in the slider and extended pneumatically in the direction of the X-ray film cassette after the upper cassette portion has been slightly pivoted to its open position starting from the cassette side facing the slider. The blast tubes are moved below the marginal area of the slightly open upper cassette portion such that the blast air emitted by them can be distributed between the lower side of the upper cassette portion and a film sheet partially adhering to said lower side so that when the upper cassette portion is fully opened, the film sheet is not moved with it but remains in the lower cassette portion.
The probes are distributed at regular intervals across the length of the slider their number is determined by the length of an X-ray film cassette of maximum size.
Owing to the great number of probes each of which is associated with a pneumatically controlled device consisting of a pressure cylinder and a piston guided therein and provided with the probe, the film-sheet releasing device as a whole is very expensive and complicated.